1. In an ester,we can identify the acid and the alcohol by a simple trick.
2. The ester group is R'-COO-R,where COO is O-C=O.
3. Here R' is attached to C=O,so it is acid and the one R attached to O is alcohol.
4. So, in C3H7COOC2H5, Acid is C3H7COOH and alcohol is C2H5OH .